1. Field of the Invention
The present invention relates to a plasma chemical reactor for processing a large size wafer. More particularly, the present invention relates to a plasma chemical reactor in which a balance adjustment unit is installed at an electrode base supporting a lower electrode of a cathode assembly for safely mounting a substrate to maintain the horizontal of the lower electrode by adjusting a height of the balance adjustment unit, thereby being capable of stably safely mounting the substrate on the lower electrode, enhancing a process uniformity of a substrate surface by plasma through maintenance of a precise balance of the substrate, and preventing a distortion or inclination of an etching profile formed in the substrate through an etching process.
2. Description of the Related Art
In general, a large size wafer for a semiconductor integrated circuit device, a glass substrate that is a main part used for a Liquid Crystal Display (LCD) or the like are to form a hyperfine structure of a desired form in a surface and form a complex-structured circuit or thin film layer, by forming several thin film layers in the surface and selectively eliminating only part of the thin film layers. Here, fabrication of thin film is achieved through many processes such as a rinse process, a deposition process, a photolithography process, a plating process, an etching process and the like.
Such a variety of processes are mainly performed within a chamber or reactor furnace that is a processing device that can isolate a wafer or substrate from the external.
Among the processes, particularly, the etching process is a process of eliminating desired materials from a wafer surface through plasma chemical reaction by spraying reaction gas (i.e., CF4, Cl2, HBr and the like) into the chamber or reaction furnace. Because the etching process is a process of forming a minute circuit in a substrate by selecting eliminating a portion not covered with photoresist using a photoresist pattern as a mask, it is of most importance to maintain plasma uniformity over the whole substrate surface, maintain the same etching rate, and maintain a substrate in a precise horizontal state to form an etching profile in a full vertical shape.
Thus, for the purpose of improving process uniformity and avoiding process failure, it is required to install a substrate in an accurate position within a chamber or reaction furnace and to maintain a precise horizontal state.
However, a conventional plasma chemical reactor does not include an adjustment device for precisely adjusting a horizontal state of a lower electrode installed in a cathode assembly and thus, has problems as follows.
First, a substrate cannot be maintained in a horizontal state and thus, is not safely mounted on the lower electrode of the cathode assembly. Also, due to substrate slip, the lower electrode is directly exposed to plasma and arc is generated, thus damaging the substrate.
Second, the lower electrode is unbalanced, thus causing a concern of a gas leakage caused by a deformation of a helium (He) gas pipe installed in the lower electrode to cool the substrate.
Third, plasma is not uniformly formed on a substrate surface, thus remarkably deteriorating process uniformity and also, an etching profile formed in a substrate in an etching process and the like is distorted or inclined, thus generating a process failure.